Sir: There is a possible explanation for Bill Bryson's spell-checker throwing up mysterious, foreign-sounding words (Bryson's America, 12 July). All modern word-processing packages contain a "custom" (ie user-specified) dictionary, as well as a standard one for most common languages. Bill has presumably spelt a word wrongly at some stage in the past and then, when running the spell-checker, has pressed "add" by mistake instead of "change".

Thus his misspelt "Internet" has been added as the new word "Internat", "falx" should have been "fax" and "phose" was presumably substituted for "phase". All custom dictionaries benefit from a good clearing out every now and then.